/*
 * Copyright 2004-2014 SmartBear Software
 *
 * Licensed under the EUPL, Version 1.1 or - as soon as they will be approved by the European Commission - subsequent
 * versions of the EUPL (the "Licence");
 * You may not use this work except in compliance with the Licence.
 * You may obtain a copy of the Licence at:
 *
 * http://ec.europa.eu/idabc/eupl
 *
 * Unless required by applicable law or agreed to in writing, software distributed under the Licence is
 * distributed on an "AS IS" basis, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
 * express or implied. See the Licence for the specific language governing permissions and limitations
 * under the Licence.
*/

package org.syntax.jedit;

import java.awt.Toolkit;
import java.awt.event.ActionListener;
import java.awt.event.InputEvent;
import java.awt.event.KeyEvent;
import java.util.Hashtable;
import java.util.StringTokenizer;

import javax.swing.KeyStroke;

/**
 * The default input handler. It maps sequences of keystrokes into actions and
 * inserts key typed events into the text area.
 *
 * @author Slava Pestov
 * @version $Id$
 */
public class DefaultInputHandler extends InputHandler {
    /**
     * Creates a new input handler with no key bindings defined.
     */
    public DefaultInputHandler() {
        bindings = currentBindings = new Hashtable();
    }

    /**
     * Sets up the default key bindings.
     */
    public void addDefaultKeyBindings() {
        addKeyBinding("BACK_SPACE", BACKSPACE);
        addKeyBinding("C+BACK_SPACE", BACKSPACE_WORD);
        addKeyBinding("DELETE", DELETE);
        addKeyBinding("C+DELETE", DELETE_WORD);

        addKeyBinding("ENTER", INSERT_BREAK);
        addKeyBinding("TAB", INSERT_TAB);

        addKeyBinding("INSERT", OVERWRITE);
        addKeyBinding("C+\\", TOGGLE_RECT);

        addKeyBinding("HOME", HOME);
        addKeyBinding("END", END);
        addKeyBinding("C+A", SELECT_ALL);
        addKeyBinding("S+HOME", SELECT_HOME);
        addKeyBinding("S+END", SELECT_END);
        addKeyBinding("C+HOME", DOCUMENT_HOME);
        addKeyBinding("C+END", DOCUMENT_END);
        addKeyBinding("CS+HOME", SELECT_DOC_HOME);
        addKeyBinding("CS+END", SELECT_DOC_END);

        addKeyBinding("PAGE_UP", PREV_PAGE);
        addKeyBinding("PAGE_DOWN", NEXT_PAGE);
        addKeyBinding("S+PAGE_UP", SELECT_PREV_PAGE);
        addKeyBinding("S+PAGE_DOWN", SELECT_NEXT_PAGE);

        addKeyBinding("LEFT", PREV_CHAR);
        addKeyBinding("S+LEFT", SELECT_PREV_CHAR);
        addKeyBinding("C+LEFT", PREV_WORD);
        addKeyBinding("CS+LEFT", SELECT_PREV_WORD);
        addKeyBinding("RIGHT", NEXT_CHAR);
        addKeyBinding("S+RIGHT", SELECT_NEXT_CHAR);
        addKeyBinding("C+RIGHT", NEXT_WORD);
        addKeyBinding("CS+RIGHT", SELECT_NEXT_WORD);
        addKeyBinding("UP", PREV_LINE);
        addKeyBinding("S+UP", SELECT_PREV_LINE);
        addKeyBinding("DOWN", NEXT_LINE);
        addKeyBinding("S+DOWN", SELECT_NEXT_LINE);

        addKeyBinding("C+ENTER", REPEAT);

        // Clipboard
        addKeyBinding("C+C", CLIP_COPY);
        addKeyBinding("C+V", CLIP_PASTE);
        addKeyBinding("C+X", CLIP_CUT);
    }

    /**
     * Adds a key binding to this input handler. The key binding is a list of
     * white space separated key strokes of the form <i>[modifiers+]key</i> where
     * modifier is C for Control, A for Alt, or S for Shift, and key is either a
     * character (a-z) or a field name in the KeyEvent class prefixed with VK_
     * (e.g., BACK_SPACE)
     *
     * @param keyBinding The key binding
     * @param action     The action
     */
    public void addKeyBinding(String keyBinding, ActionListener action) {
        Hashtable current = bindings;

        StringTokenizer st = new StringTokenizer(keyBinding);
        while (st.hasMoreTokens()) {
            KeyStroke keyStroke = parseKeyStroke(st.nextToken());
            if (keyStroke == null) {
                return;
            }

            if (st.hasMoreTokens()) {
                Object o = current.get(keyStroke);
                if (o instanceof Hashtable) {
                    current = (Hashtable) o;
                } else {
                    o = new Hashtable();
                    current.put(keyStroke, o);
                    current = (Hashtable) o;
                }
            } else {
                current.put(keyStroke, action);
            }
        }
    }

    /**
     * Removes a key binding from this input handler. This is not yet
     * implemented.
     *
     * @param keyBinding The key binding
     */
    public void removeKeyBinding(String keyBinding) {
        throw new InternalError("Not yet implemented");
    }

    /**
     * Removes all key bindings from this input handler.
     */
    public void removeAllKeyBindings() {
        bindings.clear();
    }

    /**
     * Returns a copy of this input handler that shares the same key bindings.
     * Setting key bindings in the copy will also set them in the original.
     */
    public InputHandler copy() {
        return new DefaultInputHandler(this);
    }

    /**
     * Handle a key pressed event. This will look up the binding for the key
     * stroke and execute it.
     */
    public void keyPressed(KeyEvent evt) {
        int keyCode = evt.getKeyCode();
        int modifiers = evt.getModifiers();

        if (keyCode == KeyEvent.VK_CONTROL || keyCode == KeyEvent.VK_SHIFT || keyCode == KeyEvent.VK_ALT
                || keyCode == KeyEvent.VK_META) {
            return;
        }

        if ((modifiers & ~KeyEvent.SHIFT_MASK) != 0 || evt.isActionKey() || keyCode == KeyEvent.VK_BACK_SPACE
                || keyCode == KeyEvent.VK_DELETE || keyCode == KeyEvent.VK_ENTER || keyCode == KeyEvent.VK_TAB
                || keyCode == KeyEvent.VK_ESCAPE) {
            if (grabAction != null) {
                handleGrabAction(evt);
                return;
            }

            KeyStroke keyStroke = KeyStroke.getKeyStroke(keyCode, modifiers);
            Object o = currentBindings.get(keyStroke);
            if (o == null) {
                // Don't beep if the user presses some
                // key we don't know about unless a
                // prefix is active. Otherwise it will
                // beep when caps lock is pressed, etc.
                if (currentBindings != bindings) {
                    Toolkit.getDefaultToolkit().beep();
                    // F10 should be passed on, but C+e F10
                    // shouldn't
                    repeatCount = 0;
                    repeat = false;
                    evt.consume();
                }
                currentBindings = bindings;
                return;
            } else if (o instanceof ActionListener) {
                currentBindings = bindings;

                executeAction(((ActionListener) o), evt.getSource(), null);

                evt.consume();
                return;
            } else if (o instanceof Hashtable) {
                currentBindings = (Hashtable) o;
                evt.consume();
                return;
            }
        }
    }

    /**
     * Handle a key typed event. This inserts the key into the text area.
     */
    public void keyTyped(KeyEvent evt) {
        int modifiers = evt.getModifiers();
        char c = evt.getKeyChar();
        if (c != KeyEvent.CHAR_UNDEFINED && (modifiers & KeyEvent.ALT_MASK) == 0
                && (modifiers & KeyEvent.CTRL_MASK) == 0 && (modifiers & KeyEvent.META_MASK) == 0) {
            if (c >= 0x20 && c != 0x7f) {
                KeyStroke keyStroke = KeyStroke.getKeyStroke(Character.toUpperCase(c));
                Object o = currentBindings.get(keyStroke);

                if (o instanceof Hashtable) {
                    currentBindings = (Hashtable) o;
                    return;
                } else if (o instanceof ActionListener) {
                    currentBindings = bindings;
                    executeAction((ActionListener) o, evt.getSource(), String.valueOf(c));
                    return;
                }

                currentBindings = bindings;

                if (grabAction != null) {
                    handleGrabAction(evt);
                    return;
                }

                // 0-9 adds another 'digit' to the repeat number
                if (repeat && Character.isDigit(c)) {
                    repeatCount *= 10;
                    repeatCount += (c - '0');
                    return;
                }

                executeAction(INSERT_CHAR, evt.getSource(), String.valueOf(evt.getKeyChar()));

                repeatCount = 0;
                repeat = false;
            }
        }
    }

    /**
     * Converts a string to a keystroke. The string should be of the form
     * <i>modifiers</i>+<i>shortcut</i> where <i>modifiers</i> is any combination
     * of A for Alt, C for Control, S for Shift or M for Meta, and
     * <i>shortcut</i> is either a single character, or a keycode name from the
     * <code>KeyEvent</code> class, without the <code>VK_</code> prefix.
     *
     * @param keyStroke A string description of the key stroke
     */
    public static KeyStroke parseKeyStroke(String keyStroke) {
        if (keyStroke == null) {
            return null;
        }
        int modifiers = 0;
        int index = keyStroke.indexOf('+');
        if (index != -1) {
            for (int i = 0; i < index; i++) {
                switch (Character.toUpperCase(keyStroke.charAt(i))) {
                    case 'A':
                        modifiers |= InputEvent.ALT_MASK;
                        break;
                    case 'C':
                        modifiers |= getMenuShortcutKeyMask();
                        break;
                    case 'M':
                        modifiers |= InputEvent.META_MASK;
                        break;
                    case 'S':
                        modifiers |= InputEvent.SHIFT_MASK;
                        break;
                }
            }
        }
        String key = keyStroke.substring(index + 1);
        if (key.length() == 1) {
            char ch = Character.toUpperCase(key.charAt(0));
            if (modifiers == 0) {
                return KeyStroke.getKeyStroke(ch);
            } else {
                return KeyStroke.getKeyStroke(ch, modifiers);
            }
        } else if (key.length() == 0) {
            System.err.println("Invalid key stroke: " + keyStroke);
            return null;
        } else {
            int ch;

            try {
                ch = KeyEvent.class.getField("VK_".concat(key)).getInt(null);
            } catch (Exception e) {
                System.err.println("Invalid key stroke: " + keyStroke);
                return null;
            }

            return KeyStroke.getKeyStroke(ch, modifiers);
        }
    }

    // private members
    private Hashtable bindings;
    private Hashtable currentBindings;

    private DefaultInputHandler(DefaultInputHandler copy) {
        bindings = currentBindings = copy.bindings;
    }
}
